This invention relates generally to stripping coatings from a substrate, and more specifically to the reuse of stripping compounds during stripping procedures and compounds suitable for such reuse.
Prior art strippers consist mainly of fast evaporating solvents such as methylene chloride, acetone, toluene, and methanol. These types of solvents have been associated with hazardous health effects and are prohibited for use under certain government regulations. Also, prior art stripping compositions only remain in a wet active stage for short periods of time because of their fast evaporation rate. Prior art stripping composition gives a small window of opportunity for removal because of the fast drying characteristics. If a prior art composition is not removed within a certain period of time the paint will then re-solidify.
Also, caustic agents, such as sodium hydroxide and potassium hydroxide, are used to strip paint. The high pH action of this caustic removal system breaks down the molecular bond of the paint film providing for effective paint removal. This occurs especially in the restoration of historical landmarks with accumulations of heavy paint layers. However, the high pH of caustic strippers will burn and discolor a substrate of wood and most other organic surfaces. On wood surfaces the outer cambium layer of wood will absorb potassium hydroxide and sodium hydroxide. Consequently, the outer cambium layer of wood cell will become weakened. If the high pH residue is not properly neutralized it remains in the outer wood fiber causing future paint and coating failures and premature degradation and staining. Likewise, aluminum and other metals are subject to pitting and staining from caustic strippers. Additionally, caustic strippers used in lead abatement and paint removal require removal by a licensed hazardous waste hauler and disposal at hazardous waste landfills at a cost of hundreds of dollars per 55-gallon drum.
The industry still needs a method to strip coatings from substrates that provides for ease of use, does not damage the substrate, does not release large amounts of organic solvents and minimizes hazardous waste.